Trapping Pandemis limitata (Lepidoptera: Tortricidae) moths with mixtures of acetic acid, caterpillar-induced apple-leaf volatiles, and sex pheromone

Abstract

AbstractPandemis limitata (Robinson) (Lepidoptera: Tortricidae) is one of several leaf-feeding caterpillar pests of commercial tree-fruit crops in British Columbia, Canada. Recent discovery that European Pandemis Hübner species are attracted by lures combining acetic acid and the caterpillar-induced apple-leaf volatiles, 2-phenylethanol, and phenylacetonitrile, prompted our examination of P. limitata response to these compounds. Trapping tests in organic apple orchards revealed that neither of these individual benzenoids, nor their binary combination, was attractive. Acetic acid alone was weakly attractive, but more importantly, catches increased significantly when an acetic-acid co-lure was combined with 2-phenylethanol or phenylacetonitrile, individually and together. Catches of male and female P. limitata with acetic acid+2-phenylethanol, or acetic acid+2-phenylethanol+phenylacetonitrile were similar, respectively, and both sexes were caught significantly less often in traps baited with acetic acid+phenylacetonitrile. When combined with acetic-acid co-lures, traps baited with membrane dispensers releasing 2-phenylethanol at ~1 mg/day caught significantly more moths than traps baited with rubber septa lures releasing 2-phenylethanol at ~0.6 mg/day. Moth catches in traps baited with 2-phenylethanol were unaffected when the emission of acetic-acid co-lures was increased from ~28 to 63 mg/day. Catches of male P. limitata in traps baited with sex pheromone were significantly greater than catches in traps baited with acetic acid+2-phenylethanol, or traps baited with a ternary blend of acetic acid+2-phenylethanol+sex pheromone. Catches of female P. limitata in traps baited with acetic acid+2-phenylethanol were significantly reduced when it was combined with sex pheromone. Use of the ternary acetic acid+2-phenylethanol+phenylacetonitrile blend provides an opportunity to develop multispecies bisexual trapping systems to improve management of sympatric tortricid pests currently causing economic losses in organic apples in British Columbia. More work on long-lasting release devices, nonsaturating traps, and organically acceptable killing agents are needed to develop organic mass-trapping systems.